The field of the invention relates to the manufacture of molded plastic products, and more particularly, to a flash removal apparatus for molded plastic products.
In manufacturing molded hollow plastic products, it is common to use a blow molding process. Blow molding inherently leaves flash on the bottle where the molten parison material is trapped between the mold halves. To achieve the desired final appearance and finish, the flash needs to be removed.
Flash on the bottom of the bottle has been removed with a pair of blades by disposing the bottle on top of the blades with the flash disposed between the blades. One blade is fixed and the other blade is driven between advanced and retracted positions defining closed and open positions, respectively, of the blades. Undesirably, with the stationary blade in position to receive the bottle thereon, a bottle cannot be rejected at the flash removal workstation before the flash removal operation is performed. Additionally, the arrangement with one movable blade may not properly or completely remove the flash requiring the bottle to be rejected or a secondary flash removal operation which increase the time and cost to manufacture the bottles.
A flash trimming assembly is provided which has a pair of blades driven by an actuator through a linkage assembly, simultaneously and in opposite directions, between a bottle receiving position and a closed position to aid in removing flash from a plastic product disposed on the blades. Preferably, the blades can also be moved to a fully open position to permit a bottle to pass between the blades and increase manufacturing flexibility and efficiency of the apparatus. The linkage assembly has a center link rotatable about a fixed pivot and at least one link arm connected to the center link and operably connected to the actuator to unfold and fold the linkage assembly in response to movement of the actuator between its advanced and retracted positions. The folding and unfolding of the linkage assembly moves the blades between their open and closed positions in cycles to remove flash from consecutive plastic products.
In one embodiment, the flash trimming assembly is incorporated into a rotary blow-molding machine, such as may be used for forming plastic bottles. Freshly molded bottles are positioned on the blades with the flash to be removed from a bottle received between the blades. Thereafter, the blades are moved to their closed position to engage the bottle flash from opposed sides, and the bottle is moved relative to the blades to remove the flash from the bottle. Preferably, to facilitate removing bottles which do not meet desired specifications from the system, the blades can be moved to their fully open position permitting a bottle to pass between them without removing any flash from the bottle.
Accordingly, one advantage of incorporating opposing blades that move simultaneously is the ability to accurately and repeatedly clamp the bottle flash to facilitate satisfactory removal of the flash.
Another advantage of the present invention is to provide opposed blades driven simultaneously in opposed directions of the same stroke length by a single, linear actuator. This provides a more efficient, cost-effective apparatus.
Another advantage of the present invention is to provide for an efficient process for ejecting or rejecting bottles from the molding system. By moving the opposing blades to their filly open position, the bottles can be removed from the system quickly and easily.
Another advantage of the present invention is to reduce scrap, improve efficiency, and reduce associated costs in manufacturing plastic bottles.
Another advantage of the present invention is to provide a reliable, efficient apparatus to remove flash which is of relatively simple design and economical manufacture and assembly.